AB0804 The relationship between autoantibodies and clinical symptoms in patients with inflammatory myopathy

Background Myositis-specific autoantibody (MSA) and myositis-associated autoantibody (MAA) are often detected in dermatomyositis (DM) and polymyositis (PM), and are useful diagnostic markers. In addition, autoantibodies are reportedly related to clinical symptoms, including skin findings, muscle symptoms, and interstitial lung disease, and provide information useful for medical treatment. However, the clinical significance of the presence of multiple MSA/MAA and anti-Ro52 autoantibodies has not been determined. Objectives The purpose of our study was to clarify the clinical significance of multiple MSA/MAA and anti-Ro52 autoantibodies. Methods We enrolled 58 patients diagnosed with DM and PM at Kagawa University Hospital. PM and DM were diagnosed according to the Bohan and Peter criteria.1 The patients were analysed for MSA (anti-Mi-2, anti-Jo-1, anti-SRP, anti-PL-7, anti-MDA5, anti-TIF1γ, anti-PL-12, anti-EJ, and anti-OJ) and MAA (anti-RNP, anti-Ku, and anti-PM-Scl) by ELISA (MESACUP anti-ARS, MDA5 and TIF1γ test, MBL, Nagoya, Japan) and Line blot (EUROLINE Myositis Profile 3, EUROIMMUN, Lubeck, Germany). We extracted MSA/MAA(+) and anti-Ro52(+) patients and analysed the association between the presence of multiple MSA/MAA or anti-Ro52 autoantibodies and patients’ clinical features (skin findings such as Gottron papule, heliotrope rash and mechanic’s hand, interstitial lung disease, malignancy, and arthritis). Results 53/58 patients were positive for MSA/MAA, followed by anti-Ro52 (n=27), anti-PL7 (n=12), anti-Jo1 (n=8), anti-PM-Scl75 (n=7), anti-Ku (n=6), anti-SRP (n=4), anti-EJ (n=4), anti-TIF1γ (n=4), anti-MDA5 (n=4), anti-Mi2 (n=3), anti-PL12 (n=1), anti-PM-Scl100 (n=1), and five cases were MSA/MAA(-). Five patients had multiple MSA/MAA (anti-PL-7+anti-Jo-1, anti-PL-7+anti-PL-12, anti-PL-7+anti Ku, anti-Ro52 +anti-Jo1+anti-PM-Scl75, and anti-Ro52 +anti-Jo1+anti Ku). In patients with DM/PM, anti-Ro52(+) patients were complicated by interstitial lung disease (ILD) and had a higher KL-6 value at onset (p Conclusions We hypothesise that the presence of multiple MSA/MAA may be useful for predicting ILD. However, in this study, anti-Ro52 autoantibodies did not correlate with ILD and myositis. Reference [1] Bohan, A., Peter, J.B., 1975. Polymyositis and dermatomyositis (second of two parts). N. Engl. J. Med. 292, 403–407. Disclosure of Interest None declared